The standard of a compact disc (CD) which is widespread nowadays is called a compact disc audio and based on the standard disclosed in the Red Book. On the basis of the Red Book, various formats, including a CD-ROM, have been standardized, and what is called a CD family is constructed. In the following description, a mere denomination “CD” generally indicates a disc of various formats included in the CD family. An optical disc, such as a CD or the like, is used in various fields as a recording medium for recording music data, motion image data, an application program of a game or a computer, or the like.
A conventional forming system of an optical disc will be described with respect to the case of the CD as an example. FIG. 10 is a constructional diagram of an optical disc forming system which is applied to the CD. The forming system of the CD mainly comprises: a mastering apparatus for forming a disc-master of an optical disc by a laser beam; and a molding and film forming apparatus for forming a number of disc substrates by using a stamper formed from the disc-master of the optical disc and forming a film onto each disc substrate.
The mastering apparatus to form a disc-master 320 of the optical disc comprises an EFM signal transmitting apparatus 500 and a laser beam recorder 600. A molding and film forming apparatus 700 molds a disc substrate from a stamper 330 formed from the optical disc disc-master 320 and forms a coating film, for example, a reflective film onto the disc substrate, thereby forming a recorded optical disc 360. The EFM signal transmitting apparatus 500 reads information data to be recorded from a master optical disc 310 and outputs an EFM signal formed by EFM (Eight to Fourteen Modulation) modulating the read-out signal to the laser beam recorder 600. The optical disc disc-master 320 is formed by coating a photoresist as a photosensitive material onto a glass plate. The laser beam recorder 600 irradiates a laser beam according to the EFM signal onto the optical disc disc-master 320. The photoresist film is developed and in the case of a positive type resist, the photosensitized portion is melted, a concave/convex pattern is formed on the photoresist film, and a pit train according to a predetermined format is formed on the surface of the optical disc disc-master 320.
Subsequently, on the basis of the optical disc disc-master 320, a die called the stamper 330 onto which the pit pattern of the optical disc disc-master 320 has been inversely transferred is formed. The molding and film forming apparatus 700 forms the disc substrate by using the stamper 330. Further, a coating film, such as a reflective film or the like, and a protective film are coated onto the disc substrate, so that the recorded optical disc 360 is copied. The concave/convex pattern formed on the optical disc disc-master 320 is transferred onto the disc substrate and the pit pattern is formed. A compression molding, an injection molding, a light hardening method, or the like is known as a method of forming the disc substrate.
The recorded optical disc 360 formed by the conventional optical disc forming system is not a recordable film but is a disc coated with the reflective film as a coating film and is a read only type, so that additional information cannot be recorded after the disc is formed.
In recent years, in order to manage or the like the recorded optical disc 360 on which predetermined information data has been recorded, a method of recording additional information, such as a unique identification number or the like, onto every recorded optical disc 360 is demanded. However, since the recorded optical disc 360 is manufactured by the foregoing forming step, it is difficult to record the additional information onto the recorded optical disc 360 which is obtained after it is processed by the molding and film forming apparatus 700 and on which the predetermined information data has been recorded without exerting an influence on the recorded information data.
Therefore, the conventional methods proposed as systems for recording the additional information, such as an identification number or the like, onto the recorded optical disc use a method of recording the additional information by a system different from a recording modulation system of a main signal. However, the recorded optical disc 360 on which the additional information has been recorded by those methods cannot be read out by drives other than a drive having a dedicated reading function and the additional information cannot be read out by the existing drives, so that there is a problem such that compatibility is poor.
A BCA (Burst Cutting Area) has been defined in a DVD-ROM and the additional information can be recorded there. However, such an area is provided as another area different from a main signal (EFM+modulation) portion and cannot be read out by drives other than drives having the dedicated reading function. The BCA is not applied to a DVD-Video or the like.
As mentioned above, according to the optical discs such as CD and MD based on the conventional standard and DVD disc excluding the DVD-ROM or the like, after they are once recorded, additional information, such as an identification number or the like, cannot be recorded.
The invention is made in consideration of the problems mentioned above, and it is an object of the invention to provide an optical disc medium on which additional information has been recorded onto a recorded optical disc on the basis of the conventional standard and to provide a data recording method and apparatus.